The adult mouse retina will be used as a model system for testing potentially neuroregenerative agents. A fine needle is used to produce a focal lesion of optic axons in the adult mouse retina. Selected chemical agents are then introduced into, or behind, the eye or intraperitoneally. One to two weeks later, the retinas are prepared as flat mounts, the optic axons selectively stained with silver. The specimens are examined for enhancement of axonal elongation, improvement in axonal guidance, decrease in scar tissue, and retardation of retrograde degeneration, as compared with controls. Some of the agents will be introduced in a long-term release (oil-water) vehicle, with or without accompanying DMSO to facilitate drug penetration. This method allows for rapid screening of potentially neuroregenerative agents in the mammalian visual system. In other experiments selected chemicals will be introduced into the vitreous chambers of 5-6 day-old chick embryos to test their effect on disrupting axonal guidance and fasciculation in the embryo. Such experiments may provide clues as to the mechanism of axonal guidance and fasciculation.